Study on the Synthesis and Structural Properties of Zeolite A-MgO Composite for Defluoridation of Water

Abstract

Zeolite A-MgO composite was synthesized in presence of zeolite A particles, MgCl₂ and urea solution under hydrothermal reaction at 150^oC for 5 h followed by calcination at 600°C/2 h. XRD and FTIR results showed the crystallization of MgO along with NaA zeolite crystals. Nano-sheet like MgO particles (50-70 nm) were grown onto the surface of NaA zeolite crystals (1 μm). BET surface area and pore size of the sample were found to be 69 m².g⁻¹ and 3.9 nm, respectively. XPS analysis showed the binding energies of O1s, Si2p, Na1s, Al2p and Mg2p as 531.6, 102.4, 1072.2, 74.2 and 49.9 eV, respectively. The synthesized product (1 g.L⁻¹ dose) showed 72% adsorption of fluoride (7.24 mg.L⁻¹) within 5 min and reached up to 94% for 90 min at pH 6.8. The adsorption capacity of the sample was calculated as 107.64 mg.g⁻¹ from Langmuir isotherm. The sample could be regenerated up to 5th cycle. A tentative mechanism for the adsorption of fluoride from aqueous solution by the synthesized zeolite A-MgO composite was proposed.

GRAPHICAL ABSTRACT

Keywords:

• Zeolite A-Mg O composite
• Crystallization
• Textural properties
• Defluoridation
• Kinetics model
• Adsorption isotherm